On Fri, 2022-12-02 at 19:27 +0800, Ziyang Zhang wrote:
> Sometimes "$((128 * dblksz / 40))" dirents cannot make sure that
> S_IFDIR.FMT_BTREE could become btree format for its DATA fork.
>
> Actually we just observed it can fail after apply our inode
> extent-to-btree workaround. The root cause is that the kernel may be
> too good at allocating consecutive blocks so that the data fork is
> still in extents format.
>
> Therefore instead of using a fixed number, let's make sure the number
> of extents is large enough than (inode size - inode core size) /
> sizeof(xfs_bmbt_rec_t).
>
> Suggested-by: "Darrick J. Wong" <djwong@xxxxxxxxxx>
> Signed-off-by: Gao Xiang <hsiangkao@xxxxxxxxxxxxxxxxx>
> Signed-off-by: Ziyang Zhang <ZiyangZhang@xxxxxxxxxxxxxxxxx>
New version looks much cleaner.
Reviewed-by: Allison Henderson <allison.henderson@xxxxxxxxxx>
> ---
> V2: take Darrick's advice to cleanup code
> common/populate | 28 +++++++++++++++++++++++++++-
> common/xfs | 17 +++++++++++++++++
> 2 files changed, 44 insertions(+), 1 deletion(-)
>
> diff --git a/common/populate b/common/populate
> index 6e004997..1ca76459 100644
> --- a/common/populate
> +++ b/common/populate
> @@ -71,6 +71,31 @@ __populate_create_dir() {
> done
> }
>
> +# Create a large directory and ensure that it's a btree format
> +__populate_xfs_create_btree_dir() {
> + local name="$1"
> + local isize="$2"
> + local icore_size="$(_xfs_inode_core_bytes)"
> + # We need enough extents to guarantee that the data fork is
> in
> + # btree format. Cycling the mount to use xfs_db is too slow,
> so
> + # watch for when the extent count exceeds the space after the
> + # inode core.
> + local max_nextents="$(((isize - icore_size) / 16))"
> +
> + mkdir -p "${name}"
> + d=0
> + while true; do
> + creat=mkdir
> + test "$((d % 20))" -eq 0 && creat=touch
> + $creat "${name}/$(printf "%.08d" "$d")"
> + if [ "$((d % 40))" -eq 0 ]; then
> + nextents="$(_xfs_get_fsxattr nextents $name)"
> + [ $nextents -gt $max_nextents ] && break
> + fi
> + d=$((d+1))
> + done
> +}
> +
> # Add a bunch of attrs to a file
> __populate_create_attr() {
> name="$1"
> @@ -176,6 +201,7 @@ _scratch_xfs_populate() {
>
> blksz="$(stat -f -c '%s' "${SCRATCH_MNT}")"
> dblksz="$(_xfs_get_dir_blocksize "$SCRATCH_MNT")"
> + isize="$(_xfs_inode_size "$SCRATCH_MNT")"
> crc="$(_xfs_has_feature "$SCRATCH_MNT" crc -v)"
> if [ $crc -eq 1 ]; then
> leaf_hdr_size=64
> @@ -226,7 +252,7 @@ _scratch_xfs_populate() {
>
> # - BTREE
> echo "+ btree dir"
> - __populate_create_dir "${SCRATCH_MNT}/S_IFDIR.FMT_BTREE"
> "$((128 * dblksz / 40))" true
> + __populate_xfs_create_btree_dir
> "${SCRATCH_MNT}/S_IFDIR.FMT_BTREE" "$isize"
>
> # Symlinks
> # - FMT_LOCAL
> diff --git a/common/xfs b/common/xfs
> index 8ac1964e..0359e422 100644
> --- a/common/xfs
> +++ b/common/xfs
> @@ -1486,3 +1486,20 @@ _require_xfsrestore_xflag()
> $XFSRESTORE_PROG -h 2>&1 | grep -q -e '-x' || \
> _notrun 'xfsrestore does not support -x
> flag.'
> }
> +
> +
> +# Number of bytes reserved for a full inode record, which includes
> the
> +# immediate fork areas.
> +_xfs_inode_size()
> +{
> + local mntpoint="$1"
> +
> + $XFS_INFO_PROG "$mntpoint" | grep 'meta-data=.*isize' | sed -
> e 's/^.*isize=\([0-9]*\).*$/\1/g'
> +}
> +
> +# Number of bytes reserved for only the inode record, excluding the
> +# immediate fork areas.
> +_xfs_inode_core_bytes()
> +{
> + echo 176
> +}
